Images are often used to create animation sequences, such as by deforming an image to generate another image in an animation sequence. For images represented by vector graphics, such as curves, splines (e.g., piecewise polynomials), and the like, deforming the image involves editing basis points of curves of the vector graphics. These editing techniques are extremely time consuming, especially for images consisting of a large number of curves, and require a high level of expertise on behalf of the graphic designer.
Consequently, editing techniques (e.g., animation workflows) have been recently developed that do not deform an image by direct manipulation of a curve representation of the image, but instead deform an image based on handles affixed to an image. For instance, a user may select and drag a handle on an image to deform the image. As an example, FIG. 1 illustrates example images 100 in accordance with one or more aspects of the disclosure. Images 100 includes image 102 and image 104 that both include an object, e.g., artwork. In the example in FIG. 1, image 104 has been generated by deforming the artwork of image 102. For instance, image 102 depicts a person (e.g., the artwork of image 102) having a plurality of handles inserted on the person, including handle 106-1, handle 106-2, handle 106-3, handle 106-4, handle 106-5, and handle 106-6 (collectively handles 106).
Image 104 is generated by selecting handle 106-1 on image 102 and dragging handle 106-1 towards the right (e.g., with a mouse). This dragging motion is indicated by arrow 108. Since handle 106-1 is located on the person's head in image 102, the person in image 104 is deformed according to the movement of handle 106-1 indicated by arrow 108. In this case, the person in image 104 leans to one side with a tilted head based on the movement of handle 106-1 indicated by arrow 108. To further illustrate the deformation caused by moving handle 106-1 in image 102 to generate image 104, image 102 includes indicator 110 and image 104 includes indicator 112. In image 110, indicator 110 is horizontal, while in image 104, based on the movement of handle 106-1 illustrated by arrow 108, indicator 112 in image 104 is moved from horizontal and depicts an angle of tilt of the person's head in image 104 with respect to horizontal.
The locations of handles on an image can have significant impact on the quality of images generated by deforming the image according to the handles on the image. For instance, an animation sequence generated from poorly-placed handles on an image usually looks unrealistic. Unfortunately, placing handles at locations on an image to generate a realistic animation sequence from the image usually requires experience levels beyond all but highly-trained experts. As a result, users often repeat steps in an animation process, such as by trying different handle locations, until an acceptable animation sequence is obtained. This process is both frustrating for the user and time-consuming for the user, and often produces poor animation results despite significant user effort.